Relief surfaces - RRRelief
In geography and architecture large relief surfaces are given in STL
format, but for engineering tasks often NURBS face data are needed. To
transform them, the method RRRelief was designed.

Complex Patches - RRPatch
In order to create complex patches, RRPatch allows adding curves in
order to define the inner shape of the patch. A tolerance-based
interpolation algorithm generates joinable surfaces.